dom4j解析xml文档&保存数据的乱码问题

package itcast.dom4j;

import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.junit.Test;

public class Demo {
    
    //读取xml文档第二本书的：<bookname>XXXX</bookname>
    @Test
    public void read() throws Exception{
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));
    
        Element root = document.getRootElement();
        Element book = (Element) root.elements().get(1);
        String value = book.element("bookname").getText();
        
        System.out.println(value);
    }
    
    @Test
    public void readAttr() throws Exception{
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));
    
        Element root = document.getRootElement();
        Element book = (Element) root.elements().get(1);
        String value = book.element("bookname").attributeValue("name");
        
        System.out.println(value);
    }
    
    //在第一本书上添加一个新的售价：<price>209yuan</price>
    @Test
    public void add() throws Exception{
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/book.xml"));
        
        Element book = document.getRootElement().element("书");
        book.addElement("price").setText("209yuan");
        
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("UTF-8");
        
        XMLWriter writer = new XMLWriter(new FileOutputStream("src/book.xml"),format);
        writer.write(document);
        writer.close();
    }

}

<?xml version="1.0" encoding="UTF-8"?>

<书架>
  <书>
    <bookname name="zero">java jiuyepeixunjiaocheng</bookname>
    <editor>zhangxiaoxiang</editor>
    <price>109yuan</price>
    <price>209yuan</price>
    <price>209yuan</price>
  </书>
  <书>
    <bookname name="one">javaWebprogramming</bookname>
    <editor>lihuoming</editor>
    <price>28.00yuan</price>
  </书>
</书架>